A major objective of the proposed research is to develop methods whereby the prevalence of drug use can be (a) accurately and economically estimated for specific drugs, population groups, and residential areas, (b) placed within a context of other health and social problems, and (c) related to social dimensions which characterize residential neighborhoods. The setting of this research in Dallas, Texas, a large triethnic city in the Southwest, is expected to favor the additional aims of gaining new understandings of the epidemiology of drug abuse and of developing prevalence estimates which are maximally useful in the planning of intervention programs. Based on factor analytic and clustering techniques applied to 1970 Census data, sociodemographic factors will be defined for approximately 30 resideetial areas of the city, and will then be extended to the 1974-1978 time period on the basis of local survey and other intercensal data. The resulting sociodemographic measures, along with a large number of drug, health, and social indicators, by residential areas, will constitute the independent variables in the research. Criterion variables will consist of direct estimates of the prevalence of prescribed use of psychotherapeutic drugs and the nonmedical use of various drugs, including alcohol and tobacco, by population groups of particular residential areas. These estimates will be based on a citywide school survey and a household sample survey, covering both adults and youth.